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Abstract:
How a catalyst behaves microscopically under reaction conditions, and what kinds of activesites transiently exist on its surface, is still very much a mystery to the scientific community.Here we present an in situ study on the red-ox behaviour of copper in the model reaction ofhydrogen oxidation. Direct imaging combined with on-line mass spectroscopy shows thatactivity emerges near a phase boundary, where complex spatio-temporal dynamics areinduced by the competing action of simultaneously present oxidizing and reducing agents.Using a combination of in situ imaging with in situ X-ray absorption spectroscopy andscanning photoemission microscopy, we reveal the relation between chemical and mor-phological dynamics and demonstrate that a static picture of active sites is insufficient todescribe catalytic function of redox-active metal catalysts. The observed oscillatory redoxdynamics provide a unique insight on phase-cooperation and a convenient and generalmechanism for constant re-generation of transient active sites.
